Bathtub



FIG. 1 is a side perspective view of the claimed design;

FIG. 2 is an upper perspective view of the claimed design;

FIG. 3 is an upper perspective view of the claimed design;

FIG. 4 is a side perspective view of the claimed design;

FIG. 5 is a top view of the claimed design;

FIG. 6 is a side view of the claimed design; and,

FIG. 7 is an end view of the claimed design.

The ornamental design for a bathtub, as shown and described.